1. Field
The present disclosure is directed to a method and apparatus that determine that an almost-contiguous resource allocation Additional Maximum Power Reduction (A-MPR) applies to an uplink transmission power. More particularly, the present disclosure relates to determination of uplink transmission power for contiguous, non-contiguous, and almost-contiguous resource-block allocations.
2. Introduction
Presently, wireless communication devices, such as User Equipment (UE), communicate with other communication devices using wireless signals. Carrier aggregation is a feature for increasing peak and average user throughput of UEs by enabling the UE to exploit unused resources on a secondary component carrier. In the absence of carrier aggregation, the resource blocks on the two component carriers are segregated so that UE's assigned to a first component carrier cannot be allocated unused resources on the second component carrier. Carrier aggregation is especially beneficial if the loading of the two component carriers is unbalanced so that many of the resource blocks on the second component carrier would be unused if they cannot be assigned to UE's on the first component carrier. Carrier aggregation also increases the peak data rate achievable by the UE. However, reduced transmission power levels may be required on the UE to meet emissions requirements and to limit interference into adjacent channels due to non-linear characteristics of UE power amplifiers. In some cases of uplink carrier aggregation, a required Additional Maximum Power Reduction (A-MPR) for determining uplink transmission power is large. Presently, the A-MPR allowed for uplink carrier aggregation is specified in two different ways. One way is specifically for contiguous allocations and the other way is for non-contiguous allocations.
For non-contiguous allocations, the A-MPR is a function of the allocation ratio which is defined as the ratio of the number of RB's allocated to the UE over all carriers, NRB_alloc, to the sum of the total number of RB's over the aggregated carriers NRB_agg. For contiguous allocations, the A-MPR is in tabular form and is a function of one or more of the allocation parameters RBstart, RBend, and LCRB, where LCRB is the number of contiguous RB's in the contiguous allocation.
Typically, for a given number of allocated RB's (RBalloc), the A-MPR allowed for a non-contiguous allocation is much larger than the A-MPR allocated for contiguous allocation. In particular, for an allocation ratio of 0.5, the A-MPR allowed for a non-contiguous allocation can be more than 4.5 dB greater than the A-MPR allowed for a contiguous allocation with the same allocation ratio. From a system perspective, large A-MPR is detrimental since a reduction in UE transmit power reduces the range and/or throughput achievable on the uplink.
While the contiguous A-MPR formulation is effective in reducing the A-MPR allowed to the UE, there is a problem in that contiguous allocations that span the boundary between the contiguously aggregated carriers will typically collide with the PUCCH resources that are configured at the edge of each carrier. Thus, in any subframe containing a PUCCH transmission (which is most subframes), it will not be possible to have a contiguous allocation that spans the boundary between carriers. There is a further problem that there is no clear understanding of the application of A-MPR to an almost-contiguous resource allocation spanning a boundary between two aggregated carriers that is part of a contiguous resource allocation punctured by resource blocks.
Thus, there is a need for a method and apparatus for determining that an almost-contiguous resource allocation A-MPR applies to an uplink transmission power.